Differences

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--- language:langs:chp [2023/04/09 23:28] – [Arrays: dynamic v/s non-dynamic indices] rajit
+++ language:langs:chp [2025/11/17 18:26] (current) – [Debugging and other support functions for simulation] rajit
@@ Line 156: / Line 156: @@
 ===== Advanced expression syntax =====
+==== Bitslice assignment ====
+For integer-valued variables, one can assign to some of the bits. The syntax for this is:
+<code act>
+ int<8> x;
+ ...
+ chp {
+   ...
+    x{4..2} := 4;
+   ...
+ }
+</code>
+This will update three bits of ''x'' based on the bit-pattern of the right hand side (in this case ''100'').
 ==== Channels in expressions ====
@@ Line 290: / Line 307: @@
 <code act>
 [ v = 0 -> x := x  - v
-[] ( [] i : 3 : v = i+2 -> x := x + i
+[] ( [] i : 3 : v = i+2 -> x := x + i )
 ]
 </code>
@@ Line 313: / Line 330: @@
 </code>
 where ''N'' is the number of channels in the ''I'' array. This approach ensures that index for the array ''I[]'' is always a constant.
+===== Debugging and other support functions for simulation =====
+When running CHP simulations, it is often helpful to print debugging output during CHP development. To support this, the CHP language includes the ''log()'' command.
+<code act>
+...
+chp {
+   ...
+   log ("Hello!");
+   ...
+}
+</code>
+The statement above will display ''Hello!'' on the [[tools:actsim|''actsim'']] output. The ''log'' statement can include variables and expressions as well:
+<code act>
+int x;
+...
+chp {
+    ...
+   log ("Hello, got: ", x+3, " and that's that.");
+   log ("%x This is hex: ", x+3);
+   log ("%b This is binary", x+3);
+   ...
+}
+</code>
+Booleans are displayed as integers, with ''0'' corresponding to false, ''1'' corresponding to true. Integers can also be displayed in hexadecimal, binary, or decimal (the default). The integer display mode can be changed with a prefix in a string, as shown in the example above. Other modifiers are ''%u'' for unsigned integers, and ''%d'' for signed integers.
+Other support functions of this type are:
+  * ''warn(string)'' : displays a warning
+  * ''assert(expr,string)'' : the first argument has to be an expression, and if it is non-zero then an assertion failed message is displayed.
+  * In the standard ''log'', a single line is displayed based on the items in the argument list. To split this into multiple ''log'' commands, use:
+     * ''log_st()'' : start a log message
+     * ''log_p(item,item,item...)'' : append to the output message, with the same syntax as the ''log()'' command.
+     * ''log_nl()'' : new line
 ====== The chp-txt sublanguage ======